Coded railway signaling apparatus



Filed Dec. s, (1943 QXL NMVIL L ||||||L R@ Y Nw QM NS uw. H, .f mw WM EN.m b NW d B il IL Uf Sw ww Vm Y n w v 5@ ww AIlv YN VM Patented Aug1 29,1944 UNITED STATES V:PATENT oFF-ICE Crawford E. Staples, Pittsburgh,Pa., assigner to The Union Switch &`Signal Company, Swiss- `vale, Pa., acorporation oilllfsylvania Applicationpecember 3, 1943,.Sernin).`512,723

s 'claims lol. 246-63) .My inventionrelatesto arailway signaling systemvfor use in single track stretches through which are .operatedlocomotives equipped with cab signal apparatusresponsive to now-of codedalternating current inthe track rails.

In application forLetters Patent of thefUnited States :Serial No.412,279, iiled September 25, 1941, byJames J. Van Horn, now Patent No.2,344,333,.granted March 14, 1944, there is shown a signaling system fora single track railroad over which traicfmay move in either direction.In V.the system shown in that application each tracksection in thetrackstretch, except for the portions of `the track stretch adjacent ahighway intersection orother location where short detector trackcircuits are required, is equipped with two track circuits, one for eachdirection of traic. Means .are provided to attimes supply steady'energyto either end of the vtrack stretch, while the track circuits arearranged so that when the track stretch is vacant, this steady energy iscascaded Yfrom one section to another throughout thetrackstretch toenergize traffic locking means at the other end of the track stretch andthus permit-the direction of traflic in the track stretchY to bereversed. In addition, there are means at each end of the track stretcheffective after the stretch has been conditionedv for eithervdirectionof traffic to supply coded energy to the section at the exitend of thetrack stretch, and the track circuit apparatus for each section isarranged so that this coded energy is cascadedfrom one section toanother to the entrance end of the track stretch to control the signalat the entrance end of the stretch.

. Asshown in Fig. 4 of the application identified above, where a highwaycrossing is encountered, track sectionsemploying steady energy trackcircuitsare provided on either side of the intersection tor control thehighway crossing signals; while a line circuit yis provided to carryaround the approach sections Vat the highway crossing the steady andcoded trafc governing. energy employed in the rest of the trackstretch.k

In track stretches in which are operatedlocomotives equipped withqcabsignal apparatusresponsive to ow -of coded alternating currentin thetrack Vrails it is necessary Vto arrangelthetrackway` apparatus so thatcoded alternating current is supplied to the rails of each track sectionat the exit end of the section. A v

It is an object of this invention to provide means for use in a systemofy the` type described for supplying'codedVV alternatingcurrent to thecoding relays whichcontrol the supply of coded alternating. current tothe detector track. sections are energized from the line circuit overwhich coded traffic governing energy is transmitted around the detectorsections.

' #Another object ofthe rinvention isto provide a system of the typedescribedwhich is arranged soithat one coding -relayisconnected acrossVthe line circuit `when the stretch is conditioned forone-directionoftratc and a second coding relay is connected across theline circuit `when the stretch is.conditioned. forthe other direction oftraIic.

A further object of theinvention is to provide a system .of the typedescribed which is arranged so .that .the coding relays associated Vwiththe crossing arenormally disconnected from the line circuit and. becomeconnected'thereto vonly after anapproachsectionis occupied. ...Anotherobject .of the invention vis to provide a system of the type describedwhich is arranged so that .only .one coding relay. is connected to theline circuit at .one time. l l

vOther objects. ofthe invention and features of noveltywill beapparent'from the following descriptiontakenrin connection with. theaccom-- panying drawing, the single figure of vwhich is adiagramiHustrating a section of railway-track equipped with apparatus.embodying vmy invention.l

I shall describe one'form of coded railway signaling. apparatus(embodying my invention and shallthen point out .the novelteaturesthereof in claims.

In practicing myinve'ntionI provide two cod--y ing relays at the highwayintersection and -employ one ofv these to' supply coded alternatingcur'rentzto the ...track'transformers atthis locationon movement cfatrain-through the track stretch in one direction, .andfemploy the othercodifng relaylto supply .codedalternating current tothe track'transformers' at this location Von n iove mentfof atrain through thetrack stretch in the other direction. rAs longV Vas-thel approachls'ections. arevacant the circuit of the line wires/extending aroundtheseV sections is complete-and coded or Ysteady .tra'ic .governingenergy maybe transmitted .over these 'line Wires'.between` the sectionsA.at` either side of the. approach sections,- whilethe coding relays atthe highway intersectionsare.;deenergized. When ya train enters-vanshort section which includes the highway intersection, the coding relayis maintained energized from the line wires by a circuit established byone i of the directional stickfrelays for the crossing signals, whilethe track relay for the intermediate section controls the supply ofcoded energy to the approach sections.

In the drawing there isrshown a stretch of single track railroad overwhich traffic may move in either direction. The track stretch includesan intersection with a highway vand this crossing is protected bysuitable crossing signals XS, while the track stretch is divided intorsuitable track sections for controlling the crossing signals. Thisinvention is directed to means for supplying coded alternating currentcab signal control energyv to the. short track section which includesthe highwayA crossing, and to the approach sections at either side ofthis section. This invention is not concerned with the apparatus atother points in the track stretch or at the ends of the single trackstretch except insofar as the equipment of this inventionv is intendedto operate/.in conjunction with that apparatus, and the equipment atthose locations may be constructed as shown in application Serial No.412,279 of James J. Van Horn.

* In order to simplify the disclosure and facilitate understanding ofmyinvention, only the equipment for the approach sections, and for theadjacent ends of the adjoining sections has been shown in the drawing.

The rails l and 2.0i the track stretch are divided by means of theusualfinsulated rail joints 3 into a number of track sections. Each ofthese sections is identified by the reference character T with adistinguishing prex which also identifies Vthe apparatus associated withthat section.

To facilitate description of the equipment it will be assumed that theright-hand end of the stretch is east and that the left-hand end of thestretch is west so that train movements from leftto right are eastboundand train movements from right to left are westbound.

The track section 'ICT' is a relatively short sec-y tion which includesthe highwayV intersection. This section has at one side the eastboundapproach section'Y'lBT, and at the other side the westbound approachsection IDT, while means governed by tranic conditions in these sectionsare provided to control the relay XR which gov' erns the crossingsignals XS.

, The short intermediate section 1CT is provided-for the purposeofinsuring that on move-A ment of a train through the track stretch ineither direction, operation of the crossing signals will be continueduntil the train clears the intersection. If this method of operation ofthe crossing signals is not required, the section TCT may be-omitted andthe approach sections 'BT'and 1DT. mayr adjoin.

- In the system shown in the drawing the track relays 1BTR and TDTRcooperate with the track relay 'ICTR of theintermediate section 1CT tocontrol directional stick relays WSR and ESR, andthe crossing signalcontrol relay XR.. However, the invention is not limited to the usev ofthis form of ,crossing signal control apparatus section Vand a trackrelay, designated TR with an appropriate prefix, connected across thesection rails at the other end of the section.

Each track section in the track stretch is provided with a tracktransformer at each end of the track section. These track transformersare designated TT with an appropriate prefix Vto indicate thev tracksection with which the transformer is associated, and also the end ofthe section at which it is located.

The track transformers located at the ends of sections 1BT, 'ICT and'IDT at which the Vtrack batteries are located have their primarywindings {connocted in series with the track battery, while theseprimary windings are of relatively low resistance so as not to undulyrestrict the supply of energyfrom the track batteries to the sectionrails.

The track transformers located at the track relay ends of sections havetheir primary windings connected in multiple with track relays, whileresistors are 'included in series with the track transformer windings torestrict flow of track circuit energy in these windings. The track relaywindings have such high impedance to alternating current that littleenergy from the track transformers flows in the relay windings.

As explained in the above-identified application of James J. Van Horn,each of the track sections IAT and IET is provided with two trackcircuits, one eastbound and one westbound. Each track circuit for eachof these track sections includes a code following track relay vat oneend of the track section and a track battery at the other end of thesection, and at each end of the section a coding relay CTM havingcontacts controlling connection of the associated track battery andtrack relay with the sec- Ation rails.

Each of the code following track relays has associated therewith a frontcontact repeater relay FSA and a back contact repeater relay BSA.` Therelays FSA and BSA are of a type the contacts of which are slow torelease, while each of these relays may have a snubbing resistorconnected across the terminals of its winding to increase the releaseperiod of the relay. The relays FSA rand BSA are proportioned so thattheir contacts will remain picked up throughout 'the longest codeinterval during which the supply of energy to the relay is interrupted.i e

The equipment at the highway intersection includes coding relays'CTMWand-CTME which operate as hereinafterexplained to cause codedalternatingcurrent energy to loe-supplied to section 'ICT and to sectionBT or section DT.

.The relays and other equipment except the track relays are suppliedfrom suitable sources of direct current, such as storage batteries, notshown, located at appropriate points inthe track stretch. The terminalsof these sources are designated B and C in the drawing.

The alternatingv current supplied to the track transformers may besupplied from any suitable source, not shown, the terminals of whichvare designated BX and CX in the drawing.

VThe construction and operation of the cab ksignal apparatus on thelocomotives operated in the -track stretch are not a part of thisinvention, and

have not been shown in order to simplify-the disclosure. The cab signalapparatus may be constructed as shown in Letters Patent of the UnitedStates No. 1,986,679, issued January l, 1935, to L. V. Lewis.

The equipment is shown in the condition which it assumes when the trackstretch is vacant and steady energy is supplied at the east end of thetrack stretch.v As explained in the Van Horn .application identifiedabove, steady energy is sup,- plied at the east end of the track,stretch and is cascaded from one track section to another Vto the Westend of the stretech to energize traiiic locking means at that point. Theapparatus provided by this invention for the approach sections isarranged so that on the supply of steady energy to either end of thetrack stretch it will be transmitted over a `line circuit around theapproach sections to the portionof the track `stretch at the other sideof these sections. As steady energy is supplied to the east end ofsection 'ET this energy feeds over back contacts of coding relay 'lWETCMand picks up track relay TEETR so that energy is supplied over frontcontacts 20 and .2i of track relay IEETR to line Wires 22 and 23, andover back contacts 25 and v28 of track relay 'IWATR to coding relayfmliC'IM.` The circuit of line wire 23 includes front contact 21 ofrelay l'DTR, front contacts 28 and 29 of track relay lCTR, andfront'contact 30 of track relayglBTR. f Accordingly, when sections TET,lC'I and VDT, are vacant, the circuit of line wires 22 and 23 iscomplete and ,steady energysupplied to the line wires over frontcontacts of relay 'lEETRissupplied over the line wires to relay 'FEACTMand keeps its contacts 32 and 33 picked up so that steady energy issupplied from the track battery -IEATB and from the tracktransformer'IEATB and from the track transformer EATZI I tofthe rails of sectionIAT. The steady energy supplied from track battery 'IEA'IBto the railsof section 'iATpicks up the track relay, not shown, at the West end ofthis section and .causes the supply of steady energy to be repeatedthroughout the ,other tra-ck sections to the west end of the singlevtrack stretch. As the track .stretch is vacant, energy is supplied torelay XR over the circuit which includes front contact 35 of `relay1CTR, frontcontact 36 of relay TDTR and front contact 3'! of Vrelay'IBTR so contact 38 of relay XR is picked up and interrupts the circuitof crossing signals XS .to

prevent their operation at this time.

At this time Ithe directional stick relays WSR and ESR are released,while the circuits ofthe coding relays -CTMW and CTME are interrupted so,that the contacts of these relays are released anddo not establish thevcircuits of the associated track transformers. v

kIf it is desired to condition the stretch to permit a westbound trainto pass through the stretch, means -not shown, at the right-hand or eastend of vthestretch are operated to permit clearing of the westboundsignal at that point and to cut oiT the supply of steady energy totheeast end of the stretch. When the supply of steady energy to the stretchisinterrupted', the track .relay Vfor each section releasesand .cuts offthe supply *of steadyenergy to the adjoining section so the supply ofsteady energy is cut off from the various sections in successionthroughout the and cuts 01T the supply of steady energy to linev wires22 and 23 so relay 'IEACTM releases and cuts oi the supply of energyfrom battery IEATB and transformer 'IEATT to the rails of section 'IATand connects track-relay IWATR across the section rails.

When the supply of steady energy at the west end of the stretch is cutoif, apparatus, not shown, at that location causes coded energy ofsuitable code frequency, such as 75 or 180 code frequency, to besupplied to the west end of the track stretch. The means for causingcoded energy to be supplied to the west end of the stretch are not a`part of ,this invention, and are shown and described in the applicationof J.J. Van Horn, identified above.

On the supply of coded energy to the west end of the track stretch,coded energy is cascaded through the successive track sections tosection 'IAT and coded energyis supplied over back contacts 32 and 33 ofrelay 'lEACTM to relay IWATR.. Accordingly, relay 'IWATR follows codeand energy is supplied over its front contacts 25 and 26 to line Wires22 and 23, and is supplied over vthese line wires and over back contacts20 and 2| of relay TEETR to relay IWECTM and Operates it to supply codedenergy from the track battery 'IWETB andxfrom the track transformer'IWETT to the rails of section TIET, while the track circuit apparatus,not shown, at the east end of section 'IET causes coded energy to berepeated into the adjacent section.

In addition, as a result of code following voperation or track relay'EWATR relays 'iWAFSA and TWABSA are picked up, and contact 40 of relay'IWABSA establishes thercircuit controlled by contact l of track relayIWATR for supplying energy to the primary winding of track transformerlWBTT. Accordingly, coded alter- -nating current .is supplied to 'therails ofvsection 'iBT at the exit end of the section, while the codefrequency of this energy is determined by the rate of operation of trackrelay lWATR.

When the westbound train enters section DT, track relay 'l-DTRreleasesand its contact 2l` interrupts the supply of energy over the line wires22 and 23 to coding vrelay 'EWECTM .and connects Wire 23 to one terminalof thewind'- ing g of coding relay CTMW, the other .terminal oivwhich isconnectedto wire 22.k Accordingly, relay CTMW is connected across linewires 22 and 23 and is operated by coded energy supplied to these wiresas a result of operation of relay IWATR; When coding relay CTMW isoperated by energy from line wires 22 and 23, coded energy issuppliedover front contact i3 of relay 1CTR and contact B4 of relay CTMWto the primaryr winding of track transformer lWD'I'I so that coded cabsignal control energy is supplied to the rails of section 'EDT at theexit end of the section, while the code frequency 'of this energy isgoverned by the rate of operation of relay CTMW which is determined bythe rate of `,operation oi relay 7WATR. The vcoded alternating currentsupplied to the rails of section lDT operates the cab signal .apparatuson the locomotiven this section .to provide an appropriate signalindication.

lOn coding operation of relay CTMW, coded alternating current issupplied over its contact 48 to transformer TWCTT and thus to the railsof section 'ICT to operate the cab signal equipment when the locomotiveadvances into section `lCT.

In addition, on release of relay 1DTR, its contact 36 interrupts thecircuit of relay XR so that contact 38 of relay XR releases andinitiates operation of the crossing signals XS. O'n release of relay1DTR, a pick-up circuit is established for relay WSR and includes frontContact 45 of relay 1BTR, back contact 46 of relay 1DTR, and backcontact 41 of relay ESR. Accordingly, relay WSR picks up at this time.

When the train enters section 1CT, track re? lay 'ICTR releases and itscontact 43 interrupts the circuit traced above for supplying codedalternating current to track transformer 'lWDTT, but does not affect thecircuit including contact 48 of coding relay CTMW for supplying energyto the track transformer 'IWCTT so that cab signal control energycontinues to be supplied to the rails of section ICT at the exit end ofthe section.

On release of relay 1CTR, its contact 35 establishes a stick circuit forrelay WSR. This circuit includes back contact 35 of relay lCTR and frontcontact 50 of relay WSR and maintains relay WSR picked up when relayslDTR and IBTR are both released or are both picked up.

In addition, on release of relay 1CTR, its contacts 28 and 29additionally interrupt the circuit of line Wire 23, while wire 23 isconnected over back contact 29 of relay 'lCTR and front contact I ofrelay WSR to the right-hand terminal of the winding of relay CTMW sothat relay CTMW continues to be operated by energy supplied over linewires 22 and 23 even though on release of track relay lCTR, the circuitcontrolled by, relay 'lDTR for connecting relay CTMW across the lineWires is interrupted.

When the train advances into. section 1BT, track relay IBTR releases andits contact 30 interrupts the circuit of line Wire 23 and cuts 'off thesupply of energy to coding relay C'IMW and it ceases to operate so thatenergy is no longer supplied to the track transformers TWCTT or 1WDTT.

When the train enters section 1BT, the cab signal apparatus on thelocomotive is operated by coded alternating current supplied to thesection rails through transformer IWBTT at the west end of the section.

In addition, when relay 'IBTR releases, its back contact 45 closes sothat when the train vacates section IDT, energy is supplied to relay WSRover the stick circuit which includes front contact 46 of relay 1DTR,back contact 45 of relay 'IBTR and front contact 52 of relay WSR sorelay WSR remains picked up after the train vacates section 'ICT andtrack relay TCTR picks up and its contact A35 interrupts the stickcircuit which it controls for supplying energy to relay WSR. l v

When the train advances into section TAT, track relay IWATR remainsreleased so coded energy is no longer supplied to the West end of linewires 22 and 23 and these wires are connected to coding relay 'IEACTM.

In addition, when relay 'IWATR ceases to follow code, relays TWAFSA and'IWABSA release so that contact 40 of relay 'IWABSA interrupts thecircuit of transformer TWBTT.

' When the train vacates section lCT, the track relay 'lCTR picks up andenergy is supplied over front contact 35 of relay 1CTR, front contact 36of relay 1DTR, and front contact 54 of relay WSR to relay XR so that itscontact 38 picks up to discontinue operation of the crossing signals XS.

When the train vacates section 1BT, track rellay 'IBTR picks up and itscontact, 31 completes the circuit including front contact 35 of relaylCTR and front contact 36 of relay 'IDTR for supplying energy to relayXR so that relay XR remains picked up to prevent operation of thecrossing signals. In addition, on picking up of .relay lB'I'R, itscontact 45 interrupts the stick circuit which it controls for relay WSRand relay WSR releases.

When sections IDT, 'ICT and 'IBT are vacated .and the track relays forthese sections are picked up, the circuit of the line Wires 22 and 23 iscomplete, while coding relays CTME and CTMW are both disconnected fromthe line Wires.

As explained in the above-identied application of J. J. Van Horn, steadyenergy may be supplied to the track stretch behind the train, and thissteady energy Will be cascaded throughout the track'stretch as eachtrack section is vacated. Accordingly, after the train vacates sectionlET, steady energy supplied at the east end of the section feeds overthe back contacts of coding relay 'IWECTM and picks up the contacts 20and 2l of relay 'IEETR so that the circuit of relay 'IWECTM isinterrupted and it is certain to remain released and maintain thecircuit of track relay 1EETR. In addition, When relay 'IEETR picks up,it contacts 2l and 20 connect line wires 23 and 22 to the terminals Band C of a source of current, and when relays lBTR, 'lCTRfand 'IDTR arepicked upto complete the circuit of line wires 22 and 23, energy issupplied over these line Wires and over back contacts 25 and 26 of trackrelay 'IWATR to coding relay 'IEACTM so that its contacts pick up tocause steady energy to be supplied to the rails of section 'IAT and tointerrupt the circuit of relay 'IWATR so that itlremains released andmaintains the circuit of relay 'lEACTlVL As track relay IEETR issteadily picked up, relay 'IEEBSA remains released and prevents supplyof energy to track transformer 1EDTT.

If the steady energy supplied at the east end of the track stretch isnow out off, and coded energy substituted therefor, this coded energywill be cascaded throughout the track stretch to condition the signal atthe West end of the stretch to permit an eastbound train to enter thestretch.

On movement of an eastbound train through the track stretch, theequipment at the highway crossing operates in a similar manner to thatdescribed in detail above on movement of a Westbound train through thetrack stretch.

When the stretch is conditioned for eastbound trahie, track relay lEETRfollows code and causes coded energy to be supplied to the line Wires 22and 23 at the right-hand or east end thereof, while this energy issupplied over the line Wires to relay lEACTM and operates it to causecoded energy to be supplied to the rails of section 1AT. As a result ofcodingV operation of relay 1EETR, the relays 'IEEFSA and 'IEEBSA areboth picked up and contact 5B of relay lEEBSA establishes the circuitincluding contact 51 of track relay 'IEETR for supplying coded energy totrack transformer TEDTT.

When an eastbound train enters section 1BT, track relay 'IBTR releasesand its contact 30 inrelay 1BTR to relay XR so that contact 36 of relayterrupts the circuit of line wire 23 and connects 'this line'Wire to theleft-hand terminal of. the

winding of coding relay C'IME, the other terminal of Which is connectedto Wire 22. Accordingly, re-

supplied over front contact 43 of track relay 1CTR Y and contact 58v 'ofrelay CTME to the primary winding of track transformer 1EBTT so thatcoded alternating current energy is supplied to the rails of section 1BTto operate the cab signal apparatus on the Vlocomotive present insection 1BT. In addition, on coding operation of rela;r CTME, codedalternating current is supplied over its contact 60 to transformer 1ECTTand thus to the rails of section 1CT to operate the cab signal equipmentwhen the locomotive advances. into section 1CT.v

On release of relay 1BTR, its contact 31 interrupts the circuit of relayXR and its contact 38 Vreleases and initiates operation of the crossingsignals XS. Also on release of relay 1BTR,a pick-up circuitY isestablished forl relay ESR and is traced over vfront contact 46 of relay1DTR, back contact 45 of relay 1BTR and back contact 52 of relay WSR,and relay ESR picks up at this time.

When the train advances into section 10T, track relay 1CTR releases andits contact 43 cuts off supply of energy to transformer 1EBTTbut doesnot affect the circuit controlled by contact 60 of relay C'IME forsupplying energy to transformer 1ECTT so that coded energy continues tobe supplied to the rails of section ICT to operate the cab signalapparatus While theY locomotive is in this section. i

In addition, on release of relay 1CTR, its back contact 25 establishes astick circuit for relay ESR, this circuit including front contact 6l ofrelay ESR. Also on release of relay 1CTR, its

`contacts 28 and 29 additionally interrupt the circuit of line wires 22and 23, while contact 28 connects Wire 23 over front contact63 ofrelayESR to the left-hand terminal of the Winding `of relay CTME so thatcoding relay CTME continuesl to be operated by coded energy supplied tothe line Wires 22 and 23 by track relay 1EETR.

When the train advances into section 1DT, track relay 1DTR releases andits contact 21 cuts off supply of energy over line Wires 22 and 23 tocoding relay CTME and it ceases to operate. When the train is in section1DT, the cab signal apparatus on the locomotive is operated by energysupplied from transformer 1EDTT.

When the. train advances into section 1ET, track relay 1EETR remainsreleased and connects line Wires 22 and 23 to coding relay 1WECTM, Whilerelays 1EEFSA and TEEBSA release so that energy is no longer supplied totrans.- former 1EDTT.

On release of relay 1DTR,rits back contact 46 is closed so that when thetrain vacates section 1BT and track relay 1BTR picks up, energy issupplied to relay ESR over the stick circuit which includes frontcontact 45 of relay 1BTR, back contact 46 of relay 1DTR, and frontcontact 41 of relay ESR. The energy supplied over this circuit keepsrelay ESR picked up after the train vacates section 1CT and track relay1CTR picks up.

When track relay 1CTR picks up, energy is supplied over front contact ofrelay 1CTR, front contact 65 of relay ESR, and front contact 31 of XRpicks up to discontinue operation of the crossing signals XS.

When the train vacates section 1DT, track relay 1DTR picks up and itscontact46 interrupts the stick circuit for relay ESR so that itreleases, but at this time relay XR is maintained energized by currentsupplied over front contact 36 of relay 1DTR.

When track relays 1BTR, 1CTR and 1DTR are picked up, the circuit of therlinevvires 22 and 3 is complete, and if steady energy is supplied to theWest end of the track stretch so that track relay 1WATR is picked up tocause steady energy to be supplied to the line Wires 22 and 23, thisenergy Will be supplied over the line Wires and over back contacts 20and 2l of relay 1EETR to coding relay 1WECTM so that its contacts arepicked up to cause steady energy to be supplied to the rails of section1ET and to interrupt the circuit of track relay 1EETR so it vremainsreleased and maintains the circuit of relay 1WECTM.

It Will be seen that the equipment is arranged so that, when the trackstretch isvacant, the circuit of the line wires extending around theapproach sections for the highwayA crossing is complete and coded orsteadyA energy may be transmitted over these lin'e Wires to controltraflic in the track stretch. When the stretch is vacant, the codingrelays at Ythe crossing are oleenergized and cab signal controlenergyisnot supplied to the approach sections. AAs long as one of the*approach sections is occupied, the supply of energy over the line wiresto the coding relays at the ends of the line circuit is prevented, Whileas soon as a train enters one of the approach sections, one or the otherof the coding relays at the crossing Yis connected across the line Wiresso as to be operated to supply to the track sections at the exit endsthereof coded cab signal control energy of appropriate code frequency.As the system is arranged so that only one coding relayV is connectedacross the line Wires at one time, the coding relays will not interfereWith each other, and will operate to supply to the track rails codedenergy of accu-r rate code pattern. A

While the invention has been lillustrated andr described in connection`With a' tra ck stretch equipped With signaling apparatus of thev typeshown in applicationSerial No. 412,279 ofA James J. Van Horn, in whichboth steady and coded trac governing energy is employed, the inventionis not limited to use in such situations, but is equally applicable totrack stretches equipped with signaling systems of other' types in whichcoded energy is supplied atY one end ofthe stretch at times and issupplied at the other end of the stretch at other times.

Although I have herein shown and described only one form of codedrailway signaling apparatus embodying my invention, it is understoodthat various changes and modications may be made therein within thescope of the appended claims Without 'departing from the spirit andscope of my invention. Having thus described my invention, What I claimis: 1. In cab signal energy supply means for use in a stretch ofrailroad track over which may move in either direction locomotivesequipped with cab signal` apparatus responsive to the presence ofcodedalternating current in the track rails, the rails of the track stretchbeing divided into a plurality of successive track sections 4including arst, second, a third and afourth section, said track stretch beingprovidedA with traflic governing apparatus of atype in which codedenergy is supplied to one end'of the track stretchv at given times andis supplied to the otherend of the stretch at other times, said secondVand third track sections each being provided With a track circuitincluding a track relay, a pair of line Wires substantially coexten'sivewith said second and third track sections and governed by the trackrelays of said track sections, the first and fourth track sections eachbeing provided with track circuits employing coded energy and eachhaving at the end of the section adjacent the end of the line Wirescoding means responsive to the supply of coded energy over the sectionrails from the opposite end. of the section for supplying coded energyto the line wires and for also supplying coded alternating current tothe rails of the adjoining track section, said first and fourth tracksections each being provided with coding means operated by coded energysupplied over the line wires and controlling the supply 'of coded energyto the section rails at the end of the section adjacent the line wires,in combination, a iirst coding device controlling the supply of codedalternating current to the rails of the third track section at the endof said section adjacent the second track section, a second codingdevice controlling the supply of coded alternating current to the railsof said second track section at the end of said section adjacent thethird track section,

means effective on release of the track relay for the second section toprevent the supply of energy over the line Wires to the coding means forthe rst section and to connect the second coding device across the linewires so that said second coding device is operated by coded energysupplied to said line wires at the end thereof adjacent the fourth tracksection, and means effective on release of the track relay for the thirdsection to prevent the supply of energy over the line Wires to thecoding means for the fourth section and to connect the first codingdevice across the line Wires so that said rst coding device is operatedby coded energy supplied to said line Wires at the end thereof adjacentthe rst track section.

2. In cab signal energy supply means for use in a stretch of railroadtrack over which may move in either direction locomotives equipped withcab signal apparatus responsive to the presence of coded alternatingcurrent in the track rails,-the rails of the track stretch being dividedinto the plurality of successive track sections including a nrst, asecond, a third and a fourth section, said track stretch being providedwith traic governing apparatus of a type in which coded energy issupplied to one end of the track stretch at given times and is suppliedto the other end of the stretch at other times, said second and thirdtrack sections each being provided With a track circuit including atrack relay, a pair of line wires substantially coextensive with saidsecond and third track sections and governed by the track relays of saidtrack sections, the rst and fourth track sections each being providedwith track circuits employing coded energy and each having at the end ofthe section adjacent the end of the line wires coding means responsiveto the supply of coded energy over the section rails from the oppositeend of the section for supplying coded energy to the line Wires and foralso supplying coded alternating current to the rails of the .adjoiningtrack section, said rst and fourth track sections each being pro-Wvidedf with coding means operated by coded energy supplied over theline Wires and controlling the supply of coded energy to the sectionrails at the end of the section adjacent the line Wires,

.When the track relay for, the second section is released and the trackrelay for the third section is picked up to permit energy supplied tothe line wires at the end thereof adjacent thevfourth track section tobe supplied to said second coding device, and means effective when thetrack relay lfor the third section-is released and the track relay forthe second section is picked up to permit -energy supplied to the lineWires at the end thereof adjacent` the iirstV track section to besupplied to said first coding device.

3. In cab signal energy supply means for use inl a stretch of railwaytrack over Whichmay move in either direction locomotives equipped withcab signal apparatus responsive to the presence of coded alternatingcurrent in the track rails, the rails of said track stretch beingdivided by insulated joints into an intermediate section having anapproach section at each side thereof, said approach sections and saidintermediate section each being provided with a track circuit includinga trackrelay, said track stretch being equipped With traflic governingapparatus for conditioningthe track stretch for one direction of traflicor the other and including a pair of line Wires substantiallycoextensive' with saidl approach sections and over which coded energymay be transmitted between the track sections at the sides of saidapproach sections remote from said intermediate section, said traiiicgoverning apparatus being-elfective When-.the stretch is conditioned`for either direction of traflic to cause coded alternating current tobezsupplied to the rails of the approach section in advance of saidintermediate section at the exit end of said approach section and toalso cause coded energy to be supplied to the line wires at the endthereof in advance of said inter-mediate section, in combination, acoding device controlling the supply of coded alternating current to therails of one approach section and to the rails of the intermediatesection at the'exit ends of said sections for one direction of traflic,another coding device controlling the supply of coded alternatingcurrent-toV the rails of the other approach section and to the rails ofthe intermediate section at the exit ends of said sections for the otherdirection of traic, means controlled by the track relaysiof one of saidapproach sections and oi said intermediate'section for connecting one oisaid coding` relays across said line Wires, and means controlled by thetrack relays of the other of said approach sections and of saidintermediate section. for connecting the other of said coding relaysacross said line Wires.

4. In cab signal energy supply means for use inV a stretch of railwaytrack over which may move in either direction locomotives equipped withcab signal apparatusresponsive to the presence of. coded alternatingcurrent in the track rails, the rails of said track stretchbeingfdivided by insulated joints into an intermediate section having anapproach sectionV at each side thereof, said approach sections and saidintermediate section each being provided with a track circuit includinga track relay, said track stretchv being equipped with traiiicgoverning' apparatus for conditioning the track stretch forone directionof traffic or the other and including a pair of line wires substantiallycoextensive with said approach sections andlover which coded energy maybe transmitted between the track section'sfat the sides of said approachsections remote from said intermediate section, said traflic governingapparatus being effective when the stretch is' conditioned for eitherdirection of traihcto cause coded alternating current to be supplied t'othe rails ofthe approach section in advance of' said intermediatesection at 'the exit end of" said approa-ch section and to also causecoded energy to be supplied to the line wires at the end thereof inadvance of said intermediate section, in combination, a coding devicecontrolling thesupply of coded alternating current to circuits overwhich energy is supplied to the railsy of one approach section providedthe track relay off' the intermediate section is picked up and to therails of the intermediate sectionfat the eXit ends of said sections forone direction of trac,

another coding device controlling the supply of' coded alternatingcurrent to circuits over which energy is supplied to the rails'of theother approach section provided the track relay of the intermediatesectionV is picked up and to the railsy ofv the intermediate sectionatthe eXit ends of said; sections for the other direcion of traflic. meanscontrolled by the track relays of one of saidvapproach sections and ofsaid intermediate section for connecting one of said coding relaysacross said line wires, and means controlled by the trackv relays of theother of said approach sections and of said intermediate section forconnecting the other of said coding relays across saidline wires.

5. In a cab signal energy supply means for use in a stretch of railwaytrack over which. may move in either direction locomotives equipped'with cab signal apparatus responsive to thepresence of coded`alternating current in the track rails, the rails of said track stretchbeing divided by insulated joints into an intermediate section having arst approach section at one side and a second approach section at theother side, said approach sections and said intermediate section eachbeing provided with a track circuit including a track relay, equippedwith traffic governing apparatus for conditioning the track stretch` forone direction of traic or the other and including a pair of` line wiressubstantially coextensive with said approach sections and over whichcoded energy may be transmitted between the track sections at the endsof said approach sections remote from said intermediate section, saidtraic governing apparatus being eiiective when the stretch isconditioned to permit traiiic to move from the first to the secondapproach section to cause coded alternating current to be supplied tothe` rails of the second approach section at the exit end thereof and tocause coded energy to be supplied to said line wires at the end thereofremote from said iirst section, said traiiic governing apparatus beingeffective when the stretch is conditioned to permit traffic to move fromthe second to the iirst approach section to cause coded alternatingcurrent to be supplied to the rails of the first aptothe railsv ofthesecond approach section at the end thereof' adjacent the intermediatesection and' to the rails ofthe intermediate section at the end thereofadjacent the first approach section,

means controlled' by the track relays of the first approach andintermediate sections for connecting' the first coding deviceacross'said line Wires, and' means controlled by the track relays of thesecond approach and intermediate sections for connecting'thesecondcoding device across said line Wires.

6. In a cab signal energy supply means for use in a stretch of railwaytrack over which may move in either direction locomotives equipped withcab signalapparatus responsive to the presence of' coded alternatingcurrent in the track rails, the

rails of'said track stretch being divided by insulatedfjoints into anintermediate section having a first approach section at one side and asecondV approach section at the other side, said approach sections andvsaidA intermediate section each beingprovid'edwith a track circuitincluding a trackl relay, said' track stretch being equipped withtraflic governing apparatus for conditioning thev track stretch for onedirection of traic or the other and including a pair of line Wiressubstantially coextensive with said approach sections and over whichcoded energy may be transmitted between the track sections at the endsof said appro-ach sections remote from said intermediate said trackstretch 'being' section, said trafc governing apparatus being effctivewhen the stretch is conditioned to permit trailic to move from the rstto the secondapproach section to cause coded alternating ,currentenlergyv to be supplied to said line wires-,at the end thereof remotefrom said first section, said traffic governing apparatus beingeffective when the stretch isv conditioned to permit traffic to movefrom' the second to the rst approach section to cause coded alternatingcurrent to be supplied to the rails of the rst approach section at theexit end thereof' and to cause coded energy to be supplied to said lineWires at the'end thereof remoteV from said second approach section, incombination', a rst coding device controlling the supply of codedalternating current/to circuits over which alternating current issupplied to the rails of said first approach section at the end thereofadjacent the intermediate section provided the track relay for theintermediate Section is picked up and over which alternating current issupplied to the rails of the intermediate section at the end thereofadjacent the second section, a second coding device controlling thesupply of coded alternating current to circuits over which alternatingcurrent is supplied to the rails of said second approach section at theend thereof adjacent the intermediate section provided' the` track relayfor the intermediate section is picked up and over which alternatingcurrent is supplied to the rails of the intermediate section at the endthereof adjacent the first section, means controlled by the track relaysfor thecflrst approach and Aintermediate track sections for connectingthe first coded device across saidv linew ires, and means controlled bythe track relays of the second approach and intermediate sections forconnesting the Second coding device across said line wires. v v

7. In cab signal energy supply'means` for use in a stretch of railwaytrack over which may move in either 'direction locomotives equippedwith-cab signal apparatus responsive to the presence of codedalternating current in the Ytrackrails, the rails of said track stretchbeing divided by insulated joints into an intermediate section having afirst approach lsection at one side and a second approach section at theother side, said approach sections andv said intermediate section eachbeing provided with a track circuit including a track relay, said trackstretch being equipped with traflic Y governing apparatus forconditioning the track stretch for one direction of traflic or the otherand including a pair of line Awires substantially coextensive with saidapproach sections and over which coded energy may be transmitted betweenthe track sections at the ends of said approach sections remote fromsaid intermediate section, said traffic governing apparatus beingeffective when the stretch is conditioned to permit traino to move fromthe first to the second approach section to cause coded alternatingcurrent to be supplied to the rails of the second approach section atthe exit end thereof and to cause coded energy to be supplied to saidline wires at the end thereof remote from said first section, saidtraffic governing apparatus being effective when the stretch isconditioned to permit traffic to move from the second to the iirstapproach section to cause coded alternating current to be supplied tothe rails of the iirst approach section at the exit end thereof and tocause coded energy to be supplied to said line Wires at the end thereofremote from said second approach section, in combination, a

first coding device controlling the supply of cod-` ed alternatingcurrent to the rails of said first approach section at the end thereofadjacent the intermediate section and to the rails of the intermediatesection at the end thereof adjacent the second approach section, asecond coding device controlling the supply of coded alternating currentto the rails of the second approach section at the end thereof adjacentthe intermediate section and to the rails of the intermediate section atthe end thereof adjacent the first approach section, means controlled bythe track relays of the first approach section and of the intermediatesection for supplying from said line wires to the rst coding devicecoded energy supplied to the line wires at the end thereof remote fromthe first approach section,.and means confor supplying from said linewires to the second coding device coded energy supplied to the line4Wires at the end thereof remote from said second approach section.

8. In cab signal energy supply means'for use ina' stretch of railwaytrack over which may move in either direction'locomotives equipped withcab signal apparatus responsive to the presence of coded alternatingcurrent in the track rails', the rails of said track stretch beingdivided by vinsulated joints into an intermediate section having a firstapproach section at one side and asecond approach section at the otherside, said approach sections and said intermediate section each beingprovided with a track circuit including a track relay, said trackstretch being equipped with traffic governing apparatus for conditioningthe track stretch for one direction of traflic or the other andincluding a pair of line Wires substantially coeXtensive with saidapproach sections arid over which coded energy may be transmittedbetween the track sections at the ends of said approach sections remotefrom said intermediate section, said traflic governing apparatus beingeective when the stretch is conditioned to permit traiiic to move fromthe first to the second approach section to cause coded alternatingcurrent to be supplied to the rails of the second approach section atthe exit end thereof and to cause coded energy to be supplied to saidline wires at the end thereof remote from said first section, saidtraffic governing apparatus being effective when the stretch isconditioned to permit traffic to move from the second to the iirstapproach section to cause coded alternating current to be supplied tothe rails of the rst approach section at the eXit end thereof and tocause coded energy to be supplied to said line wires at the end thereofremote from said second approach section, in combination, a first codingdevice controlling the supply of coded alternating current to circuitsover which alternating current is supplied to the rails of said firstapproach section at the end thereof adjacent the intermediate sectionprovided the track relay for the intermediate section is picked up andover which alternating current is supplied to the rails of theintermediate section at the end thereof adjacent the second section, avsecond coding device controlling the supply of coded alternating currentto circuits over which alternating current is supplied to the rails ofsaid second approach section at the end thereof adjacent theintermediate section provided the track relay for the intermediatesection is picked up and over which alternating current is supplied tothe rails of the intermediate section at the end thereof adjacent thefirst section, means controlled by the track relays of the rst approachsection and of the intermediate section for supplying from said linewires to the first coding device coded energy supplied to the line wiresat the end thereof remote from the first approach section, and `meanscontrolled by the track relays of the second approach section and of theintermediate section for supplying from said line wires to the secondcoding device coded energy supplied to the line wires at the end thereofremote from said second approach section.

CRAWFORD E. STAPLES.

